Depression Reduces Serotonin Transporter Binding Potential

But researchers find lower binding potential only in certain brain regions of depressed subjects

MONDAY, Jan. 9 (HealthDay News) -- Patients with major depression have reduced serotonin transporter binding potential in the amygdala and midbrain compared to healthy controls, according to a study published in the January issue of the American Journal of Psychiatry.

Ramin V. Parsey, M.D., of the New York State Psychiatric Institute in New York City, and colleagues used positron emission tomography to study the amygdala, hippocampus, thalamus, putamen, anterior cingulate cortex and midbrain in 25 medication-free subjects with DSM-IV major depressive disorder. They tested the subjects during a major depressive episode and compared the results to 43 healthy controls.

Although the researchers hypothesized that a lower level of serotonin transporter binding potential in all six brain regions was necessary for the expression of major depressive disorder, their analysis showed that depressed subjects had a lower level only in the amygdala and midbrain. In both brain regions, the level was 20% lower compared to controls. The researchers also found that the lower binding potential was more pronounced in the depressed subjects who had never received antidepressants.

"Previous research has suggested an association between hyperactivity in the amygdala and a greater likelihood that sensory or social stimuli are perceived or remembered as emotionally arousing or aversive; thus, hyperactivity in the amygdala may contribute to the relationship between adverse childhood experiences and adult mood disorders," the authors conclude.

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